Looking at buying a used P38 in good shape, 170k miles, but has transmission issues. Owner said it ran fine but he left it parked a while and then it had no reverse, then about 3 months later forward quit working. No check engine light, no shifter lights flashing, no dash lights flashing.

Have had several D2's and know the xyz switch issue, but don't know anything about P38's. What else should I ask/look for to understand how serious this is?

 

have you check the fluid level and condition?
unlike a DII a p-38 has a dipstick

 

Someone on another post said the rubber o-ring on the plastic piece in the transmission being incorrectly installed or leaking would suck air instead of fluid which would cause shifting problems.

 

P38 does not have a dipstick. There's a fill plug and a drain plug. You check at the fill plug.